1. Field of the Invention
The present invention relates to glycero-compounds having a triple bond and, more particularly, to novel glycero-compounds (lipids) having a triple bond which is useful as organic thin membrane materials capable of serving as a drug carrier by sealing a water soluble drug in an inner water phase of a vesicle or dissolving an oil soluble drug into a vesicle, surface modifiers of various industrial products (fiber, plastic, glass, metal, ceramic, etc.), organic thin membrane materials for modifying the surface of a biopolymer such as membrane protein or nucleic acid, and dispersing agents, emulsifiers, deemulsifiers, detergents, solubilizers, humectants and penetrants of cosmetics, foods and dyes, and to membrane forming materials containing the same
Priority is claimed on Japanese Patent Application No. 2005-322170, filed Nov. 7, 2005, the content of which is incorporated herein by reference.
2. Description of Related Art
A glycero-compound (lipid), in which one molecule of a glycerol and one or two molecules of a saturated or unsaturated fatty acid are linked through an ester bond, is widely used as treating agents for various industries used for mining, metal working, surface finishing and cleaning as well as various domestic detergents and cleaners because of its surface activity, and is also widely used as additives for drugs, cosmetics and foods because of its high safety.
A glyceryl ester of a saturated or unsaturated fatty acid of this kind is obtained by partial saponification of naturally produced triglyceride, or by linking one molecule of a glycerol and one or two molecules of a saturated or unsaturated fatty acid through an ester bond. Furthermore, a noncyclic phospholipid, in which residual hydroxyl groups are linked to a phosphoric acid group, is not only naturally produced, but also synthesized by artificial means.
Even if the glyceryl ester of the saturated fatty acid or the phospholipid derived therefrom is hydrated or not, it solidifies with no fluidity or its solid dispersion when a fatty acid chain solidifies with the decrease in temperature. It is known that the temperature at which this change occurs depends on the chain length of the fatty acid, and it solidifies at lower temperature when the chain length increases. In applications such as surface modification treatment, it becomes difficult to handle because of poor fluidity.
It is known that, in the case of the glyceryl ester of the unsaturated fatty acid or the phospholipid derived therefrom, the temperature at which it solidifies is usually lower than that in the case of the saturated fatty acid, and an unsaturated bond is oxidatively decomposed with oxygen in an air, easily. Therefore, it is difficult to apply the glycerol ester of the unsaturated fatty acid or the phospholipid derived therefrom to various uses for comparatively long period.
A lot of fatty acids and glyceryl esters, which have a double bond, exist in the natural world. Also glyceryl esters and glyceryl ethers, which have a double bond introduced therein, have hitherto been synthesized, artificially. There has also been synthesized a lipid in which an unsaturated bond such as diene (two double bonds) or diyne (two triple bonds) is conjugated so as to impart polymerizablity.
On the other hand, extremely little fatty acids having a monoyne (one triple bond) exist in the natural world. For example, fatty acids having a monoyne exist as 9-octadecynoic acid in oil extracted from seeds of plants belonging to the genus Santalaceae, as shown in non-patent document 1. However, a complex lipid containing the same such as phospholipid has never been known.
Furthermore, an ester type phospholipid having a monoyne at the end of the hydrophobic chain has been synthesized (Chem. Phys. Lipids, 112, 99-108 (2001)). However, the ester type phospholipid is not suited for use as a membrane base material for reconstituting a membrane protein because of its short chain length (13 carbon atoms) of the hydrophobic group. Also the monoyne at the end is not suited for use as a drug carrier material in the living body in view of biodegradability because of its high polymerizability.
Non-patent document 1: Tetrahedron Lett., No. 40, 3011-3013 (1964))
Non-patent document 2: Chem. Phys. Lipids, 112, 99-108 (2001)
A glyceryl ether derivative, which contains a non-polymerizable triple bond introduced therein and is chemically stable, has never been found.